Treatment of hydrocarbon oils



Patented June 19, 1934 UNITED STATES TREATMENT or HYDROCARBON OILSJacque C. Morrell, Chicago, Ill., assignor to Universal Oil ProductsCompany, Chicago, 111., a, corporation of South Dakota No Drawing.Application September 17, 1931,

Serial No. 563,460 a 4 claims. (01. 19636) V This invention relates tothe treatment of hydrocarbon oils and refers more particularly to thetreatment of relatively low boiling cracked oilsalthough distillatesfrom the straight run or non-cracking distillation of petroleum may alsobe treated.

More specifically the'invention has reference to the treatment ofhydrocarbon vapor mixtures containing substantial amounts of componentsboiling within the range of commercial gasoline and in its mostparticular aspect has reference to the treatment of the vapors producedby cracking relatively heavy hydrocarbon oils, an

improved process being disclosed which makes possible and practicablethe production of finished gasolines directly from the cracking process,thus modifying the usual steps involving the chemical treatment of lightcracked distillates and their rerunning to produce gasoline so that theliquid treating and subsequent rerunning operation can be eliminatedwith resultant savings in chemical reagents and the cost of thererunning distillation.

Petroleum distillates, especially cracked distillates, containundesirable compounds, presumably of a highly unsaturated character,

which render them unstable with respect to color,

and knock rating.

or gumming up the fuel feed linesQcarburetor, valves and other parts of,the motor. Other objectionable compounds such as those of sulphur,

the sulphuric acid fed into a system at a given temperature if it ismore dilute than that indinitrogen and the like may be present in suchdistillates, and it is among the objects of this invention to remove, orreduce to a minimurinthe objectionable substances present. in petroleum'concentration; also that for each set of condidistillates.

One of the important and desirable develop ments in petroleum refiningisthe direct pro- J 8% solution. of sulphuric acid is fed into. a tower,

the average temperature ;of which is approxi-* duction of a marketabledistillate from the cracking process. Many attempts have been made toemploy refining agents for this purpose,

particularlydirected towards the use of sulphuric acid'which, for themost part, have been unsuccessful because they have failed to take intocon- 7 sid'eration the physical and chemical properties of sulphuricacidunder-the conditions of refinsuccessfully applied 'asa refining agent tope- The development of gums may also prevent proper operation of themotorby plugging 'troleum and its products only whilein the liquidstate. 7

The following table taken from thel9l3 Edition of the Manufacture ofSulphuric Acid and Alkali by Lunge, a standard work on'the subject,shows the relationship between the boiling point and concentration ofsulphuric acid:

Table I Percent H1804 B. Pt. F.

From the above table it is evident that at a given temperature and ateach temperature the sulphuric acid exists at a. definite concentrationand thatirrespective of theconcentration of cated by the concentration.for the corresponding temperature it will concentrate to the given tionsthere is a corresponding minimum concentration. For example, if anapproximately mately 360 F., neglecting the partial pressures of thesteamrand oil vapors, the sulphuric acid introduced will concentrate toapproximately 75% :and under these temperature conditions such aconcentration of sulphuric acid will immediately attack and destroy theunsaturated hydrocarbons in the immediate vicinity, resulting in anoff-colored overhead product of high gum content and in a. charring ofthe derivatives of sulphuric acid in the hydrocarbons, plugging up thecolumn and rendering the process inoperative. The above indicates onlyapproximately the conditions existing in the tower but is sufiicient toillustrate the trend and direction of the reaction and explain whyprevious attempts to refine in the manner described have beenunsuccessful.

It is well known that concentrations of sulphuric acid which may be evensubstantially nonreactive at ordinary temperatures are highlydestructive in their reactions at elevated tem peratures. Hence while itis desirable to treat petroleum distillates in the vapor state in orderto avoid the expense of redistilling the product, it is imperative thata method of treatment be provided which will enable one to definitelycontrol the concentration and consequently the rate and kind of reactionat the elevated temperatures of treatment. The present inventionaccomplishes this aim in a new and novel manner which will behereinafter morefully described.

In one specific embodiment the invention comprises treating hydrocarbonoil vapors, especially cracked vapors, with aqueous solutions containingessentially sulphuric acid, a sulphate or acid sulphate and an oxidizingsalt or salts of oxidizing acids, or the oxidizing acids themselves.

The proportions of the three groups of treating reagents which may thusbe used in solution may be varied over a wide range depending upon theirmutual solubility, the particular chemical action required, thetemperature and pressure under which the treatment is conducted andother controllable details of operation. In regard to the sulphates oracid sulphates which may be employed, those of the alkali metals, thealkaline earth metals or the heavy metals may be used depending upontheir solubility and the other features mentioned. The salts ofoxidizing acids mentioned may be such salts as chromates, dichromates,permanganates, chlorates, nitrates, hypochlorites, molybdates,tungstates, bromates, iodates, etc., either alone or in suitableadmixtures determined again by their solubility, their treating efiectand their availability.

It will be obvious to those familiar with the chemical nature of theoxidizing salts mentioned that their reaction with heated hydrocarbonvapors will be extremely -vigorous unless modified by suitable dilution.It will also be evident to those familiar with the physics and chemistryof solutions that it is difiicult to determine the exact nature of theions present in solutions or the nature of their union with each otherexcept as evidenced by chemical and electrochemical effectscharacteristic of the solutions and the nature of the solid saltsdeposited as the solutions are progressively concentrated. The

' main and essential feature of the present invention lies in providinga series of treating solutions which may be used in treating crackedvapors to controllably oxidize, polymerize and desulphurize them.

In conducting operations comprised within the scope of the invention,hydrocarbon vapors from any source, for example, direct from a crackingprocess and in general from any distillation process includingsubstantially atmospheric pressure distillation of crudes or rerundistillations upon primary distillates may be passed through towerscontaining filling or bailiing material if desired either countercurrentto or concurrent with a solution containing regulated proportions ofsulphuric acid, acid sulphates, and oxidizing salts. The treatingsolution may be introduced in the form of a spray or mist from sprays,

atomizers or nozzles to insure intimate contact with the vaporsundergoing treatment or it may be, for example, introduced unto the toptray of a series of superimposed plates to flow downwardlycountercurrent to a rising stream of vapors. In some cases it may besufficient to introduce the vapors into the bottom of a pool of treatingreagent so that their upward passage therethrough effects the desiredtreatment. Other efiicient contacting or mixing devices such as orificecolumns may be employed. In any case of operation the treating reagentmay be introduced, the vapors withdrawn and the sludge reaction productsremoved continuously by utilizing any of the well known treating andfractionating devices common to the oil industry.

Treatments may be employed alone or as a step along with other separatetreatments such as treatment with fullers earth and preliminary or finalneutralization or sweetening of the vapors with ammonia or liquid alkalisolutions, sodium plumbite, etc., to insure the neutralization of acidiccompounds and subsequent separate treatments may also be employed. Othertypes of treatments which may be conducted as preceding or succeedingsteps following the application of the treating process of the inventionare such treatments as those accomplished by the use of metals, metaloxides, lime, etc.

In a preferred operation of the process the vapors treated arepreliminarily fractionated so that their boiling range approximates thatof commercial gasoline so that the reagent is not wasted upon portionsof the vapor mixture which are too heavy for use as motor fuel.

The sludge from the treatment may at times be recirculated, particularlyin the case of treatments involving counterfiow of reagent solution andvapors through a filled tower, such recirculation being employed toinsure maximurn efficiency in the use of the particular solutionemployed. It is further contemplated to insert a regeneration step sothat sludge produced may be used as a basis for making fresh reagent.For example, it may be diluted to separate and partially hydrolyzedissolved and emulsified oils and acid organic compounds, the aqueoussolution reconcentrated to desired strength and replenished by theaddition of calculated amounts of the chemicals necessary to restore itto the proper composition for its eifective use.

It is recognized that the employment of powerful oxidants such as thesalts of chloric, perchloric, permanganic and other acids may seem atfirst thought to be a revolutionary step in the treatment of crackedhydrocarbon vapors, but the present invention provides for the safe andcontrollable utilization of these stronger oxidizing properties by usingthe oxidizing compounds in a more or less dilute condition, this dilutecondition being due principally to the use of relatively large amountsof neutral or slightly acid of permanganate but no acid sulphate would136-.

come concentrated due to evaporation until a concentration of sulphuricacid is reached which would exert a very destructive and charring effectupon the cracked vapors and produce effects far beyond those desirable.

Owing to the possible variations in composition of treating solutionswhich may be used in conducting treatments characteristic of theinvention the number of operations and results obtainable therefrommight be considerably multipled. However, one characteristic examplewill be illustrative and will make evident at once the practicabilityand commercial advantages of the process.

The example selected may be one concerned with the treatment ofsubstantially end point vapors from cracking plant operating upon aheavy gas oil charging stock produced from California crude. Thesevapors may be passed upwardly through a tower equipped with necessarycontact surfaces counterflow to a treating solution of the followingapproximate'compositionz Percent Sulphuric acid H2804 43 Sodium acidsulphate NaHSO4 25 Sodium permanganate NaMnO4 4 Water 28 Gravity A.P.I54

Gums by copper dish method 400mg. Saybolt color 10 .Sulphur. 0.4

The gasoline produced after applying the process of the invention to thevapors prior to their condensation will be recovered in only slightlyreduced yield, say, 1% .less than that normally recoverable withouttreatment and will possess the following properties:

Sulphur Q 0.16%

The temperature at the top of the treating tower may be approximately300 F., and the pressure substantially atmospheric or slightlysuperatmospheric.

The foregoing descriptive material and example will serve to define thenature of the present invention and indicate its applicability in therefining of cracked vapors but the description and. examples areillustrative only and specific only in regard to the cases described andshould not therefore be considered as constituting limitations upon thebroad scope of the invention.

I claim as my invention:

1. In the refining of hydrocarbon distillates, the step which comprisestreating the same with an aqueous solution of sulphuric acid containinga suflicient quantity of a sulphate to prevent undue concentration ofthe solution and an oxidizing agent selected from the group consistingof the inorganic oxidizing acids and the salts thereof.

2. The step as defined in claim 1 further characterized in that saidsulphate is an acid sulphate.

3. In the refining of hydrocarbon distillates, the step which comprisestreating the same with an aqueous solution of sulphuric acid containinga suflicient quantity of a sulphate to prevent undue concentration ofthe solution and a salt of an inorganic oxidizing acid.

4. In the refining of hydrocarbon distillates, the step which comprisestreating the same with an aqueous solution of sulphuric acid'containinga sufiicient quantity of an acid sulphate to prevent undue concentrationof the solution and a salt of an inorganic oxidizing acid.

I JACQUE C. MORRELL.

